In mining and tunneling operations, roof bolts with expansion shell type anchors are used extensively. The expansion shell type anchors have proven to be ineffective in tunnel strata or mine roof strata composed of soft rock formations; consequently they contribute to unsafe working conditions in tunnels and mines. Where the pressure exerted through the expansion shell to the wall of the bolt hole exceeds the compressive strength of the rock formation, the yielding rock strata decreases the load bearing capacity of the roof bolt assembly.
The pick arm anchor assembly provides a means by which the anchoring point of the pick arm can be deeply imbedded into the wall of the bolt hole, providing a more effective anchor for the roof bolt in soft rock formations.